Immune-related bone marrow failure following anti-PD1 therapy

Fever of unknown origin associated with immune checkpoint inhibitors

Since the approval for the treatment of melanoma in 2014, immune checkpoint inhibitors (ICIs) have revolutionized the therapy pattern across various malignancies. Coinciding with their frequent usage, their adverse effects, including fever, cannot be neglected. In the context of cancer diseases and cancer treatments, fever of unknown origin (FUO), which has long posed a challenge for clinicians in terms of diagnosis and management, brings forth new connotation and significance. In this paper review, we present the concept of ICIs-associated FUO, consider activated immune system and elevated cytokines as common mechanisms by which ICIs induce fever and various immune-related adverse events (irAEs), summarize and compare the primary etiologies of ICI-associated FUO, and compare it with conventional types of FUO.

Immune checkpoint inhibitor-related acquired amegakaryocytosis thrombocytopenia: a case report and literature review

Introduction

Immune checkpoint inhibitors (ICIs) are used in several advanced malignancies and may cause various immune-related adverse events (irAEs). Among them, hematological irAEs are less described. Acquired amegakaryocytic thrombocytopenia (AAT) is a rare immune hematologic disorder characterized by severe thrombocytopenia and complete absence of megakaryocytes in bone marrow.

Case presentation

Herein, we present the case of a patient in their 40s with metastatic melanoma who developed an AAT after 12 cycles of nivolumab (anti-PD1). His platelet count decreased by ≤5 × 109/l without other cytopenia. Bone marrow biopsy showed normal cellularity with a complete absence of megakaryocyte and T-CD8+ lymphocyte infiltration. Given the failure of systemic steroids, eltrombopag was started, an oral thrombopoietin receptor agonist (TPO-RA), and his platelet count subsequently increased with complete response.

Discussion

Four other cases are described on literature with the same features than non-ICI-related AAT. All cases occurred after anti-PD/PD-L1 treatment with a median onset of 5 weeks. The presentation of our case is quite different with delayed cytopenia. Both ciclosporin and TPO-RA seem to be efficient therapies.

Conclusion

TPO-RA could be preferred in oncologic patients, but safety data are still missing to define clear guidelines for immune-related AAT management.

Exploring Immune-Related Adverse Events: A Case of Febrile Neutropenia in a Melanoma Patient Receiving Immunotherapy

Introduction

The introduction of immune checkpoint inhibitors (ICIs) has opened a new chapter in cancer treatment. Nevertheless, their use may result in immune-related adverse events (irAEs) with multifactorial determinants, complex mechanisms, and varying clinical implications. In specific cancer types, like melanoma, irAEs exhibit a complex relationship with patient outcomes.

Case Presentation

We present a case of febrile neutropenia following ICI therapy in a patient with metastatic melanoma, underscoring the intricate clinical landscape associated with irAEs in the context of cancer immunotherapy. More specifically, a 68-year-old man was diagnosed with metastatic malignant melanoma and administered a combination of nivolumab and ipilimumab. However, after a single dose, the patient was hospitalized due to febrile neutropenia. The patient eventually recovered, but a diagnosis of myelosuppression related to prior immunotherapy led to treatment discontinuation. Subsequently, the patient transitioned to a second-line therapy.

Conclusion

This case contributes to our comprehension of rare yet potentially severe hematological irAEs and their influence on immunotherapy outcomes. Such insights will guide future diagnostic and therapeutic strategies in the field of immunotherapy.

Case Report: Life-threatening pancytopenia with tislelizumab followed by cerebral infarction in a patient with lung adenocarcinoma

Immune checkpoint inhibitors (ICIs) are an integral antitumor therapy for many malignancies. Most patients show very good tolerability to ICIs; however, serious immune-related adverse events (irAEs) with ICIs have been well documented and prevent some patients from continuing ICIs or even become the direct cause of patient death. Cytopenia is a rare irAE but can be life-threatening. Here, we present the case of a 66-year-old male patient with metastatic lung adenocarcinoma who received two doses of chemotherapy + PD-1 antibody tislelizumab and developed pancytopenia after each dose. Although the first episode of pancytopenia resolved with a treatment regimen of granulocyte colony-stimulating factor (G-CSF), thrombopoietin (TPO), and red blood cell and platelet transfusion, the second episode showed extreme resistance to these treatments and improved only after the administration of steroids. His second pancytopenia episode resolved after a long course of treatment with methylprednisolone, G-CSF, TPO, hetrombopag and multiple red blood cell and platelet transfusions. However, he suffered a cerebral infarction when his platelet count was in the normal range and gradually recovered 1 week later. This case highlights the importance of the early recognition and management of hematological irAEs.

Antithymocyte globulin for aplastic anemia secondary to pembrolizumab: a case report and review of literature

Aplastic anemia is a rare but potentially serious complication of immune checkpoint inhibitor therapy. The authors present a case of pembrolizumab-induced aplastic anemia that was refractory to steroids but had some hematologic response to modified-dosing antithymocyte globulin (ATG). This is the first reported case of hematological response to ATG for immune checkpoint inhibitor-induced aplastic anemia and the first reported case of modified ATG dosing for this indication. Cases of immune checkpoint inhibitor-induced aplastic anemia and management options are also summarized. Given the high morbidity and mortality associated with ICI-induced aplastic anemia, more data is necessary to guide evidence-based management recommendations.

Immune checkpoint inhibitor-induced aplastic anaemia: Case series and large-scale pharmacovigilance analysis

Introduction: Impressive advances in immunotherapy especially immune checkpoint inhibitors have made great progress in treating multiple cancers but can also cause serious even incurable immune-related adverse events, mostly found in colitis, dermatitis, hepatitis, and thyroiditis patients. Rare autoimmune hematologic toxicities have been reported in the literature, but are poorly described. Aplastic anaemia induced by immune checkpoint inhibitors is a life-threatening autoimmune disease; however, only a few cases have been reported in the literature. Objective: To characterize and evaluate Aplastic anaemia associated with different ICI regimens in public database and review the literature. Methods: We described a case series of patients experiencing Aplastic anaemia while on immune checkpoint inhibitors. We also mined the Food and Drug Administration's Adverse Event Reporting System and used reporting odds ratio, the proportional reporting ratio, the Bayesian confidence propagation neural network and the multi-item gamma Poisson shrinker algorithms to achieve the data of the suspected adverse events of Aplastic anaemia-induced by immune checkpoint inhibitors between January 2011 and June 2022. Results: Thirteen patients with Aplastic anaemia events while on immune checkpoint inhibitors were included in our case series, and seven of them had a fatal outcome. In FAERS, a total of 38 individual case safety reports (immune checkpoint inhibitors) with different ICI regimens were retrieved, of which 25 (65.79%) were reported as monotherapy and 13 (34.2%) had a fatal outcome. The reporting odds ratio was significant for nivolumab (reporting odds ratio 3.05, 95%CI 1.73-5.38), pembrolizumab (reporting odds ratio 2.33, 95%CI 1.16-4.67), avelumab (reporting odds ratio 12.63, 95%CI 3.15-50.62) and ipilimumab/nivolumab (ROR 2.57, 95%CI 1.15-5.72). Conclusion: There is a significant reporting signal of Aplastic anaemia with several ICI agents. Clinicians should raise awareness and monitor this potentially fatal adverse event.

Immune Checkpoint Inhibitor-Related Cytopenias: About 68 Cases from the French Pharmacovigilance Database

Simple Summary

Data on immune checkpoint inhibitor (ICI)-related cytopenias are scarce. The aim of the study was to further characterize grade ≥ 2 ICI-related cytopenias using the French pharmacovigilance database. Immune thrombocytopenia and autoimmune hemolytic anemia were the most frequently reported ICI-related cytopenias (50.7% and 25.3%, respectively). Nearly half were grade ≥ 4, and 4.4% of patients died from cytopenia-related complications. Using the French pharmacovigilance database, this study provides a comprehensive analysis of ICI-related cytopenias that are rare but potentially life-threatening adverse drug reactions. Early recognition and timely initiation of appropriate treatment are key in their management in clinical practice.

Abstract

Immune checkpoint inhibitor (ICI)-related cytopenias have been poorly described. This study aimed to further characterize ICI-related cytopenias, using the French pharmacovigilance database. All grade ≥ 2 hematological adverse drug reactions involving at least one ICI coded as suspected or interacting drug according to the World Health Organization criteria and reported up to 31 March 2022, were extracted from the French pharmacovigilance database. Patients were included if they experienced ICI-related grade ≥ 2 cytopenia. We included 68 patients (75 ICI-related cytopenias). Sixty-three percent were male, and the median age was 63.0 years. Seven patients (10.3%) had a previous history of autoimmune disease. Immune thrombocytopenia (ITP) and autoimmune hemolytic anemia (AIHA) were the most frequently reported (50.7% and 25.3%, respectively). The median time to onset of ICI-related cytopenias was 2 months. Nearly half were grade ≥ 4, and three patients died from bleeding complications of refractory ITP and from thromboembolic disease with active AIHA. Out of 61 evaluable responses, complete or partial remission was observed after conventional treatment in 72.1% of ICI-related cytopenias. Among the 10 patients with ICI resumption after grade ≥ 2 ICI-related cytopenia, three relapsed. ICI-related cytopenias are rare but potentially life-threatening. Further studies are needed to identify risk factors of ICI-related cytopenias.

Treatment of patients with cancer using PD‑1/PD‑L1 antibodies: Adverse effects and management strategies (Review)

In 2020, there were an estimated 19.3 million new cancer cases and close to 10 million cancer deaths worldwide. Cancer remains one of the leading causes of death. In recent years, with the continuous improvement of our understanding of tumor immunotherapy, immunotherapeutics, such as immune checkpoint inhibitors, have gradually become a hot spot for tumor treatment. Amongst these, programmed cell death protein 1/programmed cell death protein ligand 1 (PD-1/PD-L1) related inhibitors, such as nivolumab and pembrolizumab, atezolizumab, avelumab and durvalumab have been shown to exhibit a high level of efficacy in several types of tumors. It has been confirmed that these inhibitors play an important role in the anti-tumor process, significantly improving the survival rate of patients and delaying the progress of the underlying cancer. However, its method of therapeutic interference and potential for damaging the immune system has caused concern regarding its suitability. As these adverse effects are caused by an immune response to endogenous tissues, they are designated as immune-related adverse events (irAEs). In this review, the typical irAEs reported in recent years and the management strategies adopted are highlighted, to serve as a reference in assessing the clinical response to these adverse reactions.

Management and Outcomes of Hematological Immune-related Adverse Events: Systematic Review and Meta-analysis

Data regarding clinical outcomes and management of hematological manifestations of immune checkpoint inhibition (ICI) is limited to case reports, series, and a few retrospective reviews. We aimed to determine the rate of response of hematological immune-related adverse events (irAEs) to immunosuppressive therapy. MEDLINE (OVID), EMBASE, and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched from inception to the present day. Retrospective reports were included without language restrictions. The risk of bias was evaluated with the Cochrane Collaboration's tool. The primary outcome of this study was the rate of response to immunosuppression. Eighty studies (14 case series and 66 individual case reports) were analyzed with a total of 135 patients with ICI-related hematological irAEs. Data analysis showed an average proportional response rate to immunosuppression among hematological irAE entities of 50% (range: 25%-70%). The heterogeneity index (I2) was 0% among reports within each entity. There is a wide spectrum of hematological manifestations to ICI therapy, and to date there is no large randomized-controlled trial data to evaluate the efficacy of treatment strategies for hematological irAEs. We found a variable overall response rate to immunosuppression therapy of around 50%, without statistically significant heterogeneity among different irAE types but significant differences among the different countries of publication. Future studies evaluating the optimal dose and duration of immunosuppressive agents for patients with hematological irAEs should be undertaken.

Nivolumab-Induced Autoimmune Haemolytic Anaemia and Safety of Subsequent Use of Ipilimumab: A Case Report

Autoimmune haemolytic anaemia (AIHA) is a rare immune-related adverse event and appears to be more common with anti-PD1/PDL1 than anti-CTLA4. Little is known about the safety of re-treating with anti-PD1/PDL1 or changing to anti-CTLA4. We present a case of grade 4 AIHA due to nivolumab (PD1-inhibitor) treatment in a patient with melanoma for adjuvant setting after surgery and the safeness of subsequent treatment with ipilimumab (anti-CTLA4). After the remission of AIHA with steroids, ipilimumab was started with the rationale of its different mechanism of action. Fortunately, AIHA did not recur. The mechanism by which checkpoint inhibitors cause AIHA is likely by augmenting or redirecting immune surveillance, especially by activating pre-existing red blood cell autoantibodies, but further studies must be done. To our knowledge, this is the first case published in the literature with the change of immunotherapy treatment to anti-CTLA4.

No need to hesitate: immune-related neutropenia and thrombocytopenia that improved by corticosteroids

Unlike cytotoxicity, haematological toxicity is a rare immune-related adverse event that is occasionally irreversible and refractory. A 67-year-old man was diagnosed with advanced lung squamous cell carcinoma. After 41 cycles of nivolumab as third-line chemotherapy, the patient developed severe neutropenia and thrombocytopenia. The bone marrow biopsy and serum immunological tests indicated no evidence of bone marrow failure and suggested autoimmune mature blood cell destruction. After initiating treatment with prednisolone 50 mg orally and filgrastim 75 μg subcutaneously once daily, neutropenia and thrombocytopenia recovered within four and nine days, respectively. The filgrastim was discontinued four days later, and the corticosteroid was discontinued three months later; there has been no haemocytopenia recurrence since then. The patient has remained untreated for more than two years without progression of lung cancer. In conclusion, corticosteroids should be considered for the treatment of autoimmune haemocytopenia if refractory bone marrow dysplasia can be ruled out.

A case of non-small cell lung cancer with danazol-dependent aplastic anemia induced by pembrolizumab

Programmed cell death protein 1 immune checkpoint inhibitor is an effective treatment for non-small cell lung cancer. Although hematological immune-related adverse events induced by antiprogrammed-cell-death-protein-1 immunotherapy have been reported, they are rare, and there remain many unknowns. We report the case of a 77-year-old woman with non-small cell lung cancer and pembrolizumab-induced danazol-dependent aplastic anemia. Sixteen days after she received pembrolizumab with carboplatin and pemetrexed as first-line treatments, she developed pancytopenia, including severe thrombocytopenia (1 × 10⁹/L) with oral bleeding, epistaxis, and systemic purpura. We initially diagnosed immune-related thrombocytopenia based on an elevated level of platelet-associated immunoglobulin G (922ng/10⁷ cells), but her thrombocytopenia was refractory to prednisolone (1mg/kg) and thrombopoietin receptor agonists. We eventually diagnosed aplastic anemia based on the findings of bone marrow hypoplasia. Treatment with cyclosporine and danazol 300mg (7.5mg/kg) was initiated. Eighteen days later, her blood cell count increased, and we reduced danazol to 100mg. Twenty-four days after the reduction of danazol, her platelet count dropped again to 14 × 10⁹/L; subsequently, increasing danazol improved her platelet count in a few days. Although aplastic anemia was recovered, she died owing to lung cancer progression. In this case, the thrombocytopenia was noticeable initially; however, pancytopenia appeared a month later, and we diagnosed her with aplastic anemia. Platelet counts improved rapidly with the use of danazol. No effective treatment has yet been established for aplastic anemia induced by antiprogrammed-cell-death-protein-1 immunotherapy, but our case suggests that danazol is an effective therapy.

Diagnosis and Management of Hematological Adverse Events Induced by Immune Checkpoint Inhibitors: A Systematic Review

There has been less volume of literature focusing on the Immune-related Hematological Adverse Drug Events (Hem-irAEs) of Immune Checkpoint Inhibitors (ICPis) in cancer patients. Furthermore, there has been no consensus about the management of hematological toxicity from immunotherapy in the recently published practice guidelines by the European Society for Medical Oncology (ESMO). We conducted a systematic review of case reports/series to describe the diagnosis and management of potentially rare and unrecognized Hem-irAEs. We searched Medline, OVID, Web of Science for eligible articles. Data were extracted on patient characteristics, Hem-irAEs, and management strategies. We performed quality assessment using the Pierson-5 evaluation scheme and causality assessment using the Naranjo scale. Our search retrieved 49 articles that described 118 cases. The majority of patients had melanoma (57.6%) and lung cancer (26.3%). The most common Hem-irAEs reported with ICPis (such as nivolumab, ipilimumab, and pembrolizumab) were thrombocytopenia, hemolytic and aplastic anemias. Less reported adverse events included agranulocytosis and neutropenia. Steroids were commonly used to treat these adverse events with frequent success. Other used strategies included intravenous immunoglobulins (IVIG), rituximab, and transfusion of blood components. The findings of this review provide more insights into the diagnosis and management of the rarely reported Hem-irAEs of ICPis.

Pembrolizumab-induced pancytopenia in a patient with squamous cell lung cancer

Immune checkpoint inhibitors (ICIs) are reportedly effective against many kinds of neoplasm, but may be responsible for several kinds of immune‐related adverse events (irAEs). Among these irAEs, the incidence of myelosuppression due to ICIs is relatively low. Corticosteroids are needed to control most cases of myelosuppression. Here, we report an 88‐year‐old woman with squamous cell lung cancer who was administered pembrolizumab. After five cycles of pembrolizumab, she developed severe pancytopenia. The pancytopenia improved under observation without steroid administration after cessation of pembrolizumab. During recovery from this irAE, the patient also maintained long‐term antitumor efficacy.

Key points

Significant findings of the study

There are several kinds of immune‐related adverse events. We encountered a case of pembrolizumab‐induced pancytopenia with squamous cell lung cancer.

What this study adds

Corticosteroids are needed to control most cases of myelosuppression induced by ICIs, but pancytopenia induced by pembrolizumab in our case improved without steroids.

Immune-mediated adverse effects of immune-checkpoint inhibitors and their management in cancer

Within the past decade, immune-checkpoint inhibitors (ICPIs), including anti-programmed cell death 1 (PD-1), anti-programmed cell death 1 ligand 1 (PD-L1), and anti-cytotoxic T lymphocyte antigen 4 (CTLA-4) antibodies, are undoubtfully the most remarkable advances in cancer therapy. The immune responses are modulated by these ICPIs via blocking the inhibitory PD-1/PD-L1 path and result in immune activation in the suppressive microenvironment of the tumor. While ICPIs result in benefits for numerous patients with malignancy and lead to disease control and survival, toxicity and safety problems have emerged as well. Although immune mediated adverse effects due to ICPIs could involve any organ system, skin, endocrine glands, and gastrointestinal tract, are one of the most commonly affected. Fortunately, in most of the cases, these immune‑mediated adverse effects (imAEs) are manageable, while in some cases these toxicities are fulminant and fatal and lead to the withdrawal of treatment. Numerous attempts have been started and are continuing to reduce the incidence rate of imAEs. Further studies are required for a better understanding of these imAEs, decrease the occurrence, and lighten the severity. In this work, we overview the imAEs and also, highlight the most important aspects of the imAEs management.

Pancytopenia And Limbic Encephalopathy Complicating Immunotherapy For Clear Cell Endometrial Cancer With Microsatellite Instability-High (MSI-H)

Background

Clear cell carcinoma of the endometrium (CCE) has a tendency to occur in a mismatch repair protein deficient molecular background. Treatment with immunotherapy can predict a favorable response.

Case presentation

We are presenting a 53-year-old female, diagnosed with CCE 17 years ago, who was treated initially with hysterectomy and left salpingo-oophorectomy, who relapsed a few months later, and was then treated with left pelvic mass excision and sigmoidectomy. Recently, the disease recurred as a retroperitoneal lymphadenopathy, which was resected but then relapsed locally, spread to the lungs, and progressed further after three lines of chemotherapy. On pathological review of the tumor, it was found to harbor loss of nuclear expression of MLH-1 and PMS-2. Based on a strong predictor of response to immunotherapy, pembrolizumab was tried. However, within a few days of the single dose of pembrolizumab, immune thrombocytopenia followed by pancytopenia, recurrent seizures, visual hallucination, and cerebellar signs consistent with limbic encephalitis developed, which were not responding to steroid and intravenous immunoglobulin.

Conclusion

We are presenting a case of a CCE with deficient mismatch repair that developed two autoimmune side effects, pancytopenia and limbic encephalitis, within a few days of a single injection of pembrolizumab.

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Toxicity of tumor immune checkpoint inhibitors-more attention should be paid

In recent years, immunotherapy, especially immune checkpoint inhibitors (ICIs), has achieved amazing results in the treatment of lung cancer, melanoma, renal clear cell carcinoma and other malignant tumors. Although ICIs have achieved significant efficacy in tumor treatment, the immune-related adverse events (irAEs) caused by non-specific immune activation of ICIs can directly affect the result of treatment, even threaten the life of patients. The most common form of irAEs involve the skin, lung, colon, liver and endocrine organs. However, it is noticeable that although irAEs of some organs are more common, actually any organ and tissue are likely to be affected, because of non-specific activation of the immune system. Other tissues and organs, though rare, can be more severe and even fatal, such as neurological disorders and myocarditis. Therefore, effective management of irAEs is of great importance for the efficacy of immunotherapy. This review is focused on the morbidity, clinical manifestations, diagnosis and treatment of tumor immune toxic effects.

Toxicities associated with checkpoint inhibitors-an overview

Immunotherapy has an increasing role in the management of cancer, both in metastatic disease and as an adjuvant therapy. However, sensitization of the immune system with checkpoint inhibitors comes with a unique side effect profile. Full appreciation of this can take some time to emerge as some adverse events are rare, or can be subtle and potentially overlooked. Clinician awareness of these side effects can be particularly important in patients with pre-existing autoimmune conditions. Here we describe common symptoms and diagnostic strategies for organ-specific side effects of anti-CTLA-4 and anti-PD-1/PD-L1 immunotherapy agents.

Adverse effects of immune-checkpoint inhibitors: epidemiology, management and surveillance

Immune-checkpoint inhibitors (ICIs), including anti-cytotoxic T lymphocyte antigen 4 (CTLA-4), anti-programmed cell death 1 (PD-1) and anti-programmed cell death 1 ligand 1 (PD-L1) antibodies, are arguably the most important development in cancer therapy over the past decade. The indications for these agents continue to expand across malignancies and disease settings, thus reshaping many of the previous standard-of-care approaches and bringing new hope to patients. One of the costs of these advances is the emergence of a new spectrum of immune-related adverse events (irAEs), which are often distinctly different from the classical chemotherapy-related toxicities. Owing to the growing use of ICIs in oncology, clinicians will increasingly be confronted with common but also rare irAEs; hence, awareness needs to be raised regarding the clinical presentation, diagnosis and management of these toxicities. In this Review, we provide an overview of the various types of irAEs that have emerged to date. We discuss the epidemiology of these events and their kinetics, risk factors, subtypes and pathophysiology, as well as new insights regarding screening and surveillance strategies. We also highlight the most important aspects of the management of irAEs.

Haematological immune-related adverse events with immune checkpoint inhibitors, how to manage?

Immune checkpoint inhibitors (ICIs) are changing the treatments of many patients with cancer. These immunotherapies are generally better tolerated than chemotherapy, and their adverse events are immune-related mimicking autoimmune or inflammatory conditions. Although these immune-related adverse events mainly affect the skin, endocrine glands, digestive tract, joints, liver or lungs, all the organs can be theoretically affected, and the haematopoietic system is not spared. This review of the literature will focus on the haematological immune-related adverse events (Haem-irAEs). By reviewing the largest clinical trials of ICIs, we estimate the frequency of Haem-irAEs at 3.6% for all grades and 0.7% for grades III-IV. Frequency of Haem-irAEs of all grades was found to be higher with anti-programmed cell death 1 (4.1%) or anti-programmed cell death ligand 1 (4.7%) than with anti-cytotoxic T-lymphocyte-associated protein 4 (0.5%) (p < 0.0001). From the 63 cases with Haem-irAEs reported in the literature, the mean time to the onset was found to be 10 weeks after ICI initiation, and the large range for occurrence (1-84 weeks) and the regular incidence suggest that Haem-irAEs could occur at any time after ICI therapy. Among the 63 reported cases with Haem-irAEs, the distribution was immune thrombocytopenia (n = 18, 29%), pancytopenia or immune aplastic anaemia (n = 12, 19%), neutropenia (n = 11, 17%), haemolytic anaemia (n = 10, 16%), cytokine release syndrome with haemophagocytic syndrome (n = 7, 11%) and other Haem-irAEs including bicytopenia or pure red cell aplasia (n = 5, 8%). Haem-irAEs are generally highly severe adverse reactions with a mortality rate of Haem-irAEs reported to be 14% (9 deaths among the 63 cases reported). The more severe and life-threatening Haem-irAEs were both cytokine release syndrome with haemophagocytic syndrome and pancytopenia or aplastic anaemia. Haem-irAEs induced by ICIs are potentially life-threatening. By discussing their pathophysiological aspects and clinical picture, we propose in this review clinical guidelines for management.

Safety and Tolerability of Immune Checkpoint Inhibitors (PD-1 and PD-L1) in Cancer

Immunotherapy has emerged in recent years and has revolutionized the treatment of cancer. Immune checkpoint inhibitors, including anti-cytotoxic T lymphocyte antigen-4 (CTLA-4), anti-programmed cell death-1 (PD-1) and anti-programmed cell death ligand-1 (PD-L1) agents, are the first of this new generation of treatments. Anti-PD-1/PD-L1 agents target immune cells by blocking the PD-1/PD-L1 pathway. This blockade leads to enhancement of the immune system and therefore restores the tumour-induced immune deficiency selectively in the tumour microenvironment. However, this shift in the balance of the immune system can also produce adverse effects that involve multiple organs. The pattern of toxicity is different from traditional chemotherapy agents or targeted therapy, and there is still little experience in recognizing and managing it. Thus, toxicity constitutes a real clinical management challenge and any new alteration should be suspected of being treatment-related. The most common toxicities occur in the skin, gastrointestinal tract, lungs, and endocrine, musculoskeletal, renal, nervous, haematologic, cardiovascular and ocular systems. Immune-mediated toxic effects are usually manageable, but toxicities may sometimes lead to treatment withdrawal, and even fulminant and fatal events can occur. Oncologists need to collaborate with internists, clinical immunologists and other specialists to understand, manage and prevent toxicity derived from immunotherapy. This review focuses on the mechanisms of toxicity of anti-PD-1/PD-L1 agents, and its diagnosis and management.

AIHA and Pancytopenia as Complications of Pembrolizumab Therapy for Metastatic Melanoma: A Case Report

Immunotherapy has been an emerging treatment for metastatic melanoma and several other malignancies since 2015. Hematological immune-mediated adverse effects from immunotherapy are rarely reported but they can cause serious harm to patients. Antibodies such as ipilimumab, nivolumab and pembrolizumab target different immune checkpoints to promote T cell anti-tumour response. In particular, pembrolizumab is an antibody that inhibits programmed cell death receptor 1 (PD-1) to upregulate tumour suppression. In this report, we present a case of pembrolizumab-induced autoimmune hemolytic anemia and pancytopenia in a patient who was receiving pembrolizumab treatment for metastatic melanoma. This patient has a history of chronic lymphocytic leukemia and was diagnosed with metastatic melanoma in 2017. He developed symptomatic AIHA and pancytopenia after receiving 8 cycles of pembrolizumab in 2018. Pembrolizumab treatment was discontinued and he was treated with blood transfusion and prednisone. After 5 months of tapering prednisone treatment, his anemia and pancytopenia have improved toward successful recovery. Cancer patients already face an increased risk of immunosuppression with conventional chemotherapy. This case report also summarized all reported cases of PD-1 inhibitor hematological adverse effects in the treatment of oncological diseases. These incidents reflect the risk of immune-mediated hematologic adverse effects, which should be considered in all patients using immunotherapy.

Hematological Side Effects of Immune Checkpoint Inhibitors: The Example of Immune-Related Thrombocytopenia

Immune-related hematological adverse events are amongst the rare but potentially life-threatening complications of immune checkpoint inhibitors. The spectrum of these toxicities is broadening as the number of patients exposed to these agents is increasing. Yet, they are still relatively unknown to many clinicians, possibly due to a lack of specific diagnostic criteria, which poses a challenge for their recognition and proper reporting, and partly due to their low incidence, often too low to be noted in most clinical trial publications. Since early detection and prompt intervention are crucial to prevent fatal consequences, it is of outmost importance that medical staff and patients be aware of these potential toxicities and learn to recognize and treat them adequately. This publication outlines strategies and offers guidance on the detection, diagnosis, risk assessment, monitoring and management of immune-related thrombocytopenia, a relatively common example of immune-related hematological toxicity of immune checkpoint inhibitors.

Haematological immune-related adverse events induced by anti-PD-1 or anti-PD-L1 immunotherapy: a descriptive observational study

BACKGROUND

Anti-programmed cell death 1 (PD-1) and anti-programmed cell death ligand 1 (PD-L1) antibodies are novel immunotherapies for cancer that can induce immune-related adverse events (irAEs). These adverse events can involve all organs, including the haemopoietic system. Thus far, haematological irAEs (haem-irAEs) have not been extensively characterised. This study aims to provide a comprehensive report of the haem-irAEs induced by anti-PD-1 or anti-PD-L1.

METHODS

In this descriptive observational study, we included consecutive patients aged at least 18 years with grade 2 or worse haem-irAEs induced by anti-PD-1 or anti-PD-L1 immunotherapy registered in three French pharmacovigilance databases: the Registre des Effets Indésirables Sévères des Anticorps Monoclonaux Immunomodulateurs en Cancérologie (REISAMIC; a prospective registry of patients treated with anti-PD-1 or anti-PD-L1 at a single centre), the ImmunoTOX committee of Gustave Roussy (a national referral database of suspected irAEs in patients treated with immunotherapy), and the registry of the Centre de Référence des Cytopénies Auto-Immunes de l'Adulte (CeReCAI; a national database of autoimmune cytopenias). Cases were reviewed by a central committee; adverse events had to be classed as certainly or probably related to anti-PD-1 or anti-PD-L1 therapy, and their severity was assessed according to the Common Terminology Criteria for Adverse Events (version 4.03). The primary endpoint was clinical description of haem-irAEs, as reported in all databases, and their frequency, as reported in the prospective REISAMIC registry.

FINDINGS

We screened 948 patients registered in the three databases from June 27, 2014, to June 29, 2018 (745 from REISAMIC, 190 from the ImmunoTOX committee, and 13 from CeReCAI). 35 patients (21 men and 14 women) with haem-irAEs related to anti-PD-1 or anti-PD-L1 were included in the study. Of 745 patients in the REISAMIC registry treated with anti-PD-1 or anti-PD-L1, four had haem-irAEs, giving a frequency of 0·5%. Median age in the 35 patients was 65 years (IQR 51-75), and the most common tumour types were melanoma (15 [43%] patients), non-small-cell lung cancer (12 [34%] patients), and lymphoma (four [11%] patients). 20 (57%) patients received nivolumab, 14 (40%) received pembrolizumab, and one (3%) received atezolizumab. Among the 35 patients, neutropenia, autoimmune haemolytic anaemia, and immune thrombocytopenia were the most common types of haem-irAE (each in nine patients [26%]), followed by pancytopenia or aplastic anaemia (five patients [14%]), bicytopenia (one patients with thrombocytopenia plus anaemia and one patient with neutropenia plus anaemia [6%]), and pure red cell aplasia (one patient [3%]). The maximum grade of severity was grade 2 in three (9%) patients, grade 3 in five (14%) patients, and grade 4 in 25 (71%) patients; two (6%) patients died from febrile neutropenia during haem-irAE related to anti-PD-1. Haem-irAEs resolved in 21 (60%) of the 35 patients.

INTERPRETATION

Haem-irAEs induced by PD-1 or PD-L1 inhibitors are rare but potentially life-threatening events. The most common clinical presentations are neutropenia, autoimmune haemolytic anaemia, immune thrombocytopenia, and aplastic anaemia. Investigations into earlier detection and better management are warranted.

FUNDING

Gustave Roussy and Gustave Roussy Immunotherapy Program.

PD-1 deficiency augments bone marrow failure in a minor-histocompatibility antigen mismatch lymphocyte infusion model

Although PD-1 blockade has revolutionized cancer immunotherapy, immune-related adverse events (irAEs) present life-threatening complications. Recent reports of aplastic anemia (AA) as irAEs implicate PD-1/PD-L1 as important in preventing immune-mediated destruction of the hematopoietic niche. Infusion of PD-1-deficient (PD-1 knockout [KO]) lymph node (LN) cells into minor-antigen mismatched mice resulted in early mortality, as well as more severe bone marrow (BM) hypoplasia, anemia, and BM microarchitecture disruption in PD-1 KO LN-infused mice relative to mice that received B6 LN cell infusion. Mice that received PD-1 KO LN cells had more CD8⁺ T-cell infiltration of the BM and greater expansion of H60-specific CD8⁺ T cells than did their B6 LN-infused counterparts. In the spleen, CD8⁺ T cells were skewed to an effector memory phenotype, suggesting accelerated differentiation of PD-1 KO T cells. Our data suggest that PD-1 dysregulation has a role in murine BM failure and vigilance in irAE monitoring may be desirable to treat early AA and related cytopenias.